In order to know whether a human being is young or old, offer it food of different kinds at short intervals. If young, it will eat anything at any hour of the day or night.
I've always been a fast reader. Now I had to do it slowly, discussing each sentence. And every time I wanted to change something I had to come up with an intelligent defense I could be pretty sure that they would turn my suggestion down, as they had so many aspects to keep in mind. However, if I argued well, I could have a chance. I had to think of every comma, every word.